The term “continuous elongated member” used in the present invention applies to pipelines and cables of finite length, but much longer than the gripper.
Continuous elongated members are laid both on land and on underwater beds, normally to transport fossil fuel and electric power over distances of kilometers; are normally buried and circular in cross section; and are handled using grippers comprising jaws with grip surfaces complementary to the shape and size of the continuous elongated member, as shown, for example, in GB 2,364,758. Using this type of gripper, the jaws must be adapted to continuous elongated members of different diameters, to achieve a sufficient grip surface area along the jaws.
Another type of gripper, described in GB 2,448,829, is used to temporarily connect equipment to the end of an underwater pipeline, or to two facing ends of two separate underwater-pipeline portions, and comprises a tubular structure; and inflatable rings housed inside the tubular structure, and which are selectively brought into contact with the outer surface of the pipeline or pipeline portions. This type of gripper also fails to effectively grip continuous elongated members of widely differing diameters, on account of each ring being designed for a circular-section pipeline slightly smaller in diameter than the inside diameter of the tubular structure. Moreover, the rings fail to define a sufficiently large grip surface area.
Continuous elongated members may even have non-circular, irregularly shaped cross sections, and, in fact, are known to be defined by a number of adjacent, connected pipes, or by bundles of cables. Which means the cross sections may assume any number of shapes, for which known grippers fail to provide a sufficiently large grip surface area.